Technical Field of the Invention
The present invention relates to liposomal lupeol acetate (Lipo-LA) and its use in the treatment or prevention of rheumatoid arthritis (RA). Especially, of the present invention relates to a method for preventing and/or treating inflammation in the progression of rheumatoid arthritis (RA) by inhibiting osteoclast generation with the administration of the liposomal lupeol acetate.
Background
Rheumatoid arthritis (RA) is a chronic autoimmune disorder that basically results in a symmetry, multi-joint, small joint inflammatory disease that may affect many tissues and organs, but principally attacks flexible (synovial) joints, and cause the disintegration of articular cartilage and bone injuries. It can be a swelling and painful condition, which can lead to joint deformity at late stage and substantial loss of functioning and mobility.
Rheumatoid arthritis is closely correlated with excessive activation of macrophages. The release of cytokines due to macrophage activation will attract more immune cells to infiltrate, result in more severe inflammatory response. Macrophages may differentiate into osteoclasts and lead to bone erosion in the joint cavity, which is the main reason for the progression of RA.
The major pharmaceuticals used in clinical treatment of RA are steroids, non-steroid anti-inflammation drugs, and certain biological agents against cytokine, such as TNF-α blockers, anti-IL-1β, anti-IL-6 antibodies, and the like (Breedveld F C. Arthritis Res 2002, 4(2):27). Such therapeutic agents are not only expensive, but also possess certain degree of side effects. The most commonly used agent is methotrexate, which is usually the first treatment to improve symptoms, decrease joint damage, and improve overall functional abilities. However, the pathogenesis of RA is not very clear so far, and known therapeutic drugs and biologics for clinical use do not effectively cure rheumatoid arthritis and will produce side effects. Therefore, it is necessary to find a more effective and safe drug for the treatment of rheumatoid arthritis.
Lupeol acetate (LA), a type of triterpene, is an ingredient in the extraction of Shea nut, and existed in the mango, cabbage and green pepper. Lupeol acetate has a chemical structure similar to sterols, and has been known with capability of anti-inflammation, antioxidation, anticancer and immunomodulation (see, Akihisa T et al., J Oleo Sci 2010, 59(6):273-280; Saleem M. Cancer Lett 2009, 285(2):109-115; Siddique H R, Saleem M. Life Sci 2011, 88(7-8):285-293). It is also demonstrated that LA can effectively mitigate the inflammatory condition induced by carrageenan in mice (Lucetti D L et al. J Inflamm 2010, 7(60)).
In addition, US Patent Application no. 20120177754 has disclosed extraction of lupeol acetate from Boswellia frereana, and the significant therapeutic effect of lupeol acetate in inhibiting inflammation and treatment of rheumatoid arthritis, but the animal model experiments show that long-term use of high doses (100 mg/kg, 12 days) is necessary for rheumatoid arthritis treatment in mice even a highly pure extract of natural lupeol acetate (95%) is used in the therapy.
Liposome is a spheroid formed by phospholipid bilayers, in which a hydrophilic drug may be coated in the inner hydrophilic cavity, lipophilic drugs may be carried by interspersing among the lipids. In one embodiment of the invention, two kinds of lipids egg phosphatidylcholine (EPC) and polyethylene glycol-distearoylphosphatidylethanolamine (PEG-DSPE) were used. EPC is a kind of phospholipid extracted from egg, and PC is the major component of cell membrane. Although PC is widespread in the organism, it is a less stable factor in lipid layer for that PC has an unsaturated fatty acid long-chain at the lipophilic terminus, in which the unsaturated bonds will confer a greater bending on the carbon chain, resulting in unclose integration with the adjacent phospholipids in the arrangement of lipid bilayer structure. While PEG-DSPE is a more stable lipid than PC for having no interference from the unsaturated bond, so it can be arranged closely to the adjacent phospholipid and form a more compact lipid layer.
Therefore, the present invention contemplates to prepare lupeol acetate liposomes for achieving effects of better suppression of inflammation and bone erosion by using the characteristics of liposome that has a longer in vivo residence time for not being susceptible to metabolism, and may cause larger space for accumulation between the vessel wall in the target treating area.